Salmon Run May Be Best Of The Last As Numbers Decline, Biologists Worry About The Future

There may never again be this many young Snake River salmon headed for the Pacific Ocean.

“This is not a great year, or most of those stocks wouldn’t be listed as endangered. But it’s all downhill from here,” Michelle DeHart, director of the Northwest Fish Passage Center, said Tuesday from Portland.

“After this year, the numbers are dropping to levels we’ve never seen before.”

So the migrating “Class of ‘95” is getting a lot of attention. It’s big for two reasons:

There’s a relatively large number of 1-year-old spring and summer chinook, produced by 28,900 adults that returned in 1993. (The next year, only 3,900 adults came back to spawn.)

In an experiment to save the virtually extinct sockeye, scientists captured the last few returning adults. They mixed the sperm and eggs in a hatchery, and last year released the offspring into Central Idaho’s Redfish Lake. Ten thousand young sockeye are expected to head for the sea later this spring.

It’s hard for some people to understand that wild sockeye and chinook, which once returned inland by the millions to spawn, are rapidly disappearing.

Biologist Ed Buettner has a firm grasp on the idea - just as firm as the grip he had Monday on a silvery spring chinook in his left hand.

Buettner was working on a fish trap that’s anchored in the Snake River near the Lewiston-Clarkston bridge. His right hand held an epidermic needle. He used it to inject a clear capsule into the salmon’s belly.

The capsule, the size of a rice grain, contained an electronic tag. Its code of 16 letters and numerals is unique.

“Like a Social Security number,” Buettner said.

This fish was a hatchery-bred chinook, not a wild one. Buettner could tell because a top fin had been clipped off.

While there are still many more hatchery fish than the endangered wild fish, their numbers are also dropping dramatically. Like its wild cousins, this smolt would have to get past the same eight Snake and Columbia River dams and reservoirs.

Four of the dams have sensors that can read the tags. Computers record the time that each young fish swims past.

Fish and Game captures, then releases, about 1 percent of the ocean-bound salmon and steelhead trout that pass its three traps on the Snake, Clearwater and Salmon rivers.

About one-tenth of those are tagged. From 1989 to 1993, that was 446,494 fish.

How many made it back as adults? Only 369 reached Lower Granite Dam, the last dam they cross on their way to spawning streams. The rest were killed by turbines, predators, fishermen and assorted environmental problems.

While the dams are a major cause of salmon decline, they are also one reason that the decline is so well documented. The most important numbers gathered are the counts of adult fish swimming up the dams’ fish ladders.

Spring chinook are the first adult fish to head upstream each year. So far this year, the number returning is about 10 percent of the average number that returned over the last decade.

By Monday, 380 wild and hatchery chinook had made it past Bonneville, the dam closest to the ocean. Only one had made it as far as Lower Granite.

While the adult numbers are a sure sign of success or decline, it’s the migration of the young, oceanbound fish that affects how the river system is operated. The Idaho Fish and Game traps and other sources of information help the Northwest Fish Passage Center decide the best time to ask that more water be released from behind dams.

The idea is to speed up downstream migration, and ultimately help more fish survive to adulthood. But water releases are a tough political call, especially in drought years when water for power production and irrigation is limited.

“To make the best use of the limited water we have, we have to know when the fish are here,” said Buettner.

After nearly a decade of drought, the region was blessed with average or better snowfall in much of the region this year. This week, Buettner is hoping for warm rains to melt that snow and send it into the rivers.

Does a faster downstream trip really mean more fish will return as adults? Many people, including those in the hydropower industry and Buettner’s boss, Gov. Phil Batt, say there’s no proof of that. They’re upset that a federal recovery plan for the endangered salmon is based largely on the notion that faster water means more returning adults.

Buettner knows the relationship hasn’t been proven, but he’s convinced it exists.

One indication, he said, is that there are more wild fish nests two and three years after streamflows are high. That suggests that when young fish move more quickly to the sea, they are more likely to return to spawn.

Thanks to the fish tagging, Buettner said, he has seven years of solid evidence that faster flows do indeed help young salmon move more quickly through the rivers.

MEMO: Cut in the Spokane edition